Explain the principles behind nuclear magnetic resonance (NMR) spectroscopy and its applications in structural elucidation and chemical analysis.

NMR spectroscopy is a powerful analytical technique based on the interaction of atomic nuclei with an external magnetic field and electromagnetic radiation. When placed in a magnetic field, atomic nuclei with nonzero spin, such as ¹H, ¹³C, and ¹⁹F, absorb and emit radiofrequency radiation at characteristic frequencies proportional to their chemical environment. By measuring the absorption and emission spectra of nuclei in a sample, NMR spectroscopy provides detailed information about molecular structure, conformation, and dynamics. Applications of NMR spectroscopy include structural elucidation of organic and inorganic compounds, identification of unknown substances, quantitative analysis of mixtures, and investigation of biomolecular interactions in biological systems.